This invention relates in general to cartridge magazines for firearms, and in particular relates to drum magazines for column-feed firearms such as carbines or the like.
The increased cartridge-holding capacity of a drum magazine, compared to a linear or column-feed magazine, is known, and drum magazines have been used with various firearms. Drum magazines are generally designed for use with a particular firearm, which was itself designed specifically to accomodate a drum magazine. one such prior art drum magazine is shown in U.S. Pat. No. 2,131,412 to Ostman.
Such prior-art drum magazines generally cannot be used or easily adapted for use with carbines or other firearms designed to receive a linear magazine, inasmuch as such drum magazines have no provision for feeding cartridges along the existing magazine-receiving receptacle of the gun. In the case of firearms such as the M-16/AR-15, a drum magazine requires an extension several inches long, to fit within the magazine receptacle for feeding cartridges from the drum to the receiver of the firearm. This magazine extension should perpendicularly join the drum magazine to avoid upsetting the longitudinal center of gravity of the firearm. The requirement for a perpendicular magazine extension creates problems in feeding all cartridges from the drum to the firearm. The need for dependable feeding of cartridges through the cartridge path within the drum, as firing progresses, also presents problems.
Reloading the magazine is another problem associated with drum magazines. Although the magazine can be partially disassembled by removing a cover and exposing the cartridge receiving channel therein, this procedure has certain faults. For example, dirt or other foreign objects can become lodged in the opened magazine, possibly causing the magazine to jam or feed improperly. Moreover, removable covers or other components can easily become damaged or lost.